Wash. Rev. Code § 81.04.020
Each commissioner shall have power to administer oaths, certify to all official acts, and to issue subpoenas for the attendance of witnesses and the production of papers, waybills, books, accounts, documents, and testimony in any inquiry, investigation, hearing, or proceeding in any part of the state.
The superior court of the county in which any such inquiry, investigation, hearing, or proceeding may be had, shall have power to compel the attendance of witnesses and the production of papers, waybills, books, accounts, documents, and testimony as required by such subpoena. The commission or the commissioner before which the testimony is to be given or produced, in case of the refusal of any witness to attend or testify or produce any papers required by the subpoena, shall report to the superior court in and for the county in which the proceeding is pending by petition, setting forth that due notice has been given of the time and place of attendance of said witnesses, or the production of said papers, and that the witness has been summoned in the manner prescribed in this chapter, and that the fees and mileage of the witness have been paid or tendered to the witness for his or her attendance and testimony, and that the witness has failed and refused to attend or produce the papers required by the subpoena, before the commission, in the cause or proceedings named in the notice and subpoena, or has refused to answer questions propounded to him or her in the course of such proceeding, and ask an order of said court, compelling the witness to attend and testify before the commission. The court, upon the petition of the commission, shall enter an order directing the witness to appear before said court at a time and place to be fixed by the court in such order, and then and there show cause why he or she has not responded to said subpoena. A copy of said order shall be served upon said witness. If it shall appear to the court that said subpoena was regularly issued by the commission, the court shall thereupon enter an order that said witness appear before the commission at said time and place as fixed in said order, and testify or produce the required papers, and upon failing to obey said order, said witness shall be dealt with as for contempt of court.
RCW 81.04.020